Intraoperative mydriasis by intracameral injection of mydriatic eye drops: in vivo efficacy and in vitro safety studies

Background: This study investigated the efficacy and safety of intracameral injection of commercially available eye drops containing 0.5% tropicamide and 0.5% phenylephrine hydrochloride (Mydrin‐P, Santen Pharmaceutical, Osaka, Japan). Design: In vitro experiment and prospective clinical study at a private hospital. Participants and Samples: Mydrin‐P was applied to confluent cultured human corneal endothelial cells, and the cellular morphology was examined. Clinical study subjects were 65 eyes of 65 patients that underwent phaco‐emulsification and aspiration with intraocular lens implantation and received intracameral injection of Mydrin‐P for poor mydriasis after preoperative topical instillation of mydriatics (intraocular mydriasis group; with five subgroups based on cause: diabetes, pseudo‐exfoliation, post‐surgery, uveitis, unknown). Controls, comprising 39 eyes of 39 patients, were not injected with Mydrin‐P. Methods: The ratio of pupillary diameter to corneal diameter was determined before and after injection of Mydrin‐P. Corneal endothelial density was measured preoperatively and 3 months and 1 year postoperatively. Main Outcome Measures: Pupillary diameter and corneal endothelial density. Results: Human corneal endothelial cell morphology was unaltered after Mydrin‐P injection. The mean ratio of the pupillary diameter to corneal diameter increased in the intraocular mydriasis group (before: 54.2 ± 4.8%, after: 58.4 ± 6.6%; P